Foil bags are commonly used as packaging for liquids or pasty masses. For example, drinks, animal foods, creams, dyes, soaps, etc. are often packaged in foil bags. Foil bags of this kind can, for example, have three sheets of foil: two side foil sheets and a bottom foil sheet.
One known way of forming a foil bag is welding pieces of foil together at the respective edges. This can be accomplished with a hot sealing method or using ultrasonic sealing.
One common drawback of the foil bags known in the art is that the weld seams occasionally have relatively small, but undesired leaks.
One object of the invention is to create an apparatus and a method for producing a weld seam on a foil bag, as well as a foil bag itself, having improved weld seams.